It has a 2 part head, the valves, and valvetrain mount on the inner section, while the camshafts mount in the outer section. If you look carefully you can see some damage on the far side of the cam carrier.

The intake valves are 35mm, the intake throat measures 30.8mm, or 88% of the valves diameter.

The exhaust valves are 29mm, the exhaust throat measures 24mm, or 83% of the valves diameter.

This doesn't look good.... not only is the one pair of ports longer, and more oddly shaped(more drag??), but they are narrower as well??? Can't tell for sure until I get this on the bench... but I do not expect equal results......

oldeskewltoy wrote:This doesn't look good.... not only is the one pair of ports longer, and more oddly shaped(more drag??), but they are narrower as well??? Can't tell for sure until I get this on the bench... but I do not expect equal results......

more to come........

That's interesting. The only thing I can think of, is maybe they made the odd side narrower to keep the air flowing at the same rate. What the longer side lacks in volume, makes up in velocity?

a little off topic, but I read an interesting article that rumored that Yamaha helped develop this version of the boxer motor. It makes sense, since Yamaha was the mastermind behind the 4ag, and all the other famous Toyota motors. So even though its made by Subaru, i'd say its still in the Toyota family if Yamaha was behind t